The aim of the proposed work is to develop information necessary for understanding the stereochemistry of intermolecular interactions in monolayers at the air-water interface. This will be done primarily through the use of Langmuir film-balance techniques to measure the effect of changes in molecular structure, temperature, and subphase composition on the surface tension surface potential and surface velocity of monolayers spread from chiral surfactants. In order to elucidate the effect of molecular structure on chiral aggregation in monolayers, a series of structurally related fatty acid derivatives will be synthesized and highly purified. Surface properties of the pure enantiomers will be compared with each other (as a check against artifacts) and with the racemic mixture to find the conditions for enantiomeric interactions. Diastereomeric interactions will also be studied by comparing the properties of mixtures of different chiral surfactants. Structural variation of single chain chiral fatty acids will emphasize variation of the head group. Synthetic methods for developing such a series are well established. A second series of chiral surfactants will include fatty acid derivatives of pharmacologically (e.g amphetamine, ephedrine, pseudoephedrine, adrenalin). Our present work lies in this series and again synthesis is a minor problem compared to purification. We propose to develop the study of enantiomeric and diastereomeric interaction in films of purified phospholipids through the rates and equilibrium properties of penetration of enantiomeric drugs into the films. Our aim is to clarify the factors of molecular structure, temperature and pH which are of greatest importance in determining stereoselectivity in interfacial systems.